Not if they existed long enough in the past. Say, before the last ice age, and were centered on Mars, not Earth.
I would say that they became too dependent on technology, and just steadily stagnated until their society collapsed from pure neglect once a large solar flare came around.
Of course, the lack of fossil fuels would probably be a pretty big warning sign, but it would make most of OTL history go as normal until the 21st century.

By "common biological anchestry" means came from the same homo line.
Well, that's what we might do. Problem is that there's inevitably going to be a number of people illegally migrating, or giving birth on Mars, so there should be contingency for such a thing.
Money makes the world go around, science and governments be dammed. You might be able to make a nature preserve of Mars when no one really seriously considers much of an economic use out of Mars... until of course, we get something like the OTL fur trade. Antarctica isn't likely to remain a nature preserve after the Antarctic Treaty expires.
All it takes for a nation to gain a monopoly on a marginally profitable Mars market is one nation that is powerful enough, that refuses to sign a UN Treaty. And there's nothing anyone can really do once that can of worms is opened.

I meant birth rates would be higher on Mars regardless of the species.
Most industry will probably be at or near earth, and Mars is harder to get off than the Moon, or a NEO. Meaning Mars is a loss from the beginning. Some natives may be employed, like in OTL fur trade (though for speciality crops and animals instead)- but there's probably not much to do otherwise until we get the proper infrastructure and tech to cut launch costs from gravity wells sufficiently enough.
#offtopic

Those aren't so much "megalopolises". Megalopolises describe a chain of cities, or a single, huge city.
https://en.wikipedia.org/wiki/Megalopolis
It's also sort of a natural urban planning idea due to it allowing for increased use of cheaper public transport (ie conspiracy theorists with Agenda 21 and all :P)
A future world almost entirely automated would have a bigger social problem with crime than anything.
When people have nothing to do, and no visible way they can see to improve themselves, socialist programs allowing them to live decently or not, a lot turn to crime and/or despair.
Same thing happens in American ghettos to an extent. Dystopian image of the future, truly.

The government might sponsor flights and training if the prospect of a colony is profitable enough. Which would require very cheap rockets, and would likely be mostly cash crops at first, since non biological matter is easy to get on the Moon.
But yeah, Russian Alaska is likely a good analogue here. Rarely profitable or barely profitable colonies with high levels of autonomy.
Not many people would get to Mars, at least not in the first 100-200 years- they didn't in America OTL, and global population numbers will likely stagnate or decline by the 2100s due to demographic trends.
Not really a cold war thing, unless both superpowers were competing for a strategic land mass.
They would likely out-breed the colonists at first too. The most likely thing to change is how many of them survive, not how many are born. That usually actually declines with better medical tech :P.
I read somewhere that birth rates usually tend to be higher in "frontier areas" where there are few people, and land for population to grow. I might be wrong, since I can't find the source for this.
Nomadic tribes tend not be very populous though. There might be native agricultural 'nations', closer to the equator, where there would be enough people to actually make this viable. It's definitely not Africa, where the colony is almost entirely going to be composed of natives, with the colonists essentially making up the upper class.
Maybe somewhere in between?
But that's assuming there's much of an economic reason to do so. It might just be "living space" for colonists wanting a job, or leaving Earth (forced or otherwise)- on land good enough to make a living, bu tnot enough to export much.
From a purely economical standpoint, Astroidal and Lunar colonies are always going to be the resource havens and moneymakers supplying orbital industry. Or I would think.
So I would think that the great powers settle their land claims in some UN conference, and concentrate their efforts and wars outside the gravity well of Mars. At least until we have something that really cuts launch costs. Space elevators, anyone?

...I'm going to say that's not really a view shared amongst the right in general- citing things like Muslims throwing gays off roofs, cited as part of the 'culture' of Islamic Middle Eastern culture.
So Plan B is still possible under a somewhat more limited extent, depending on the politics of a colony.
Which would provide some interesting population mechanics between the more tolerant and less tolerant colonies.
Why? Is it that hard to make basic fabrics on Mars with 3D printing?
Far bigger problem for "them", than "us"- I would think. Americaplague never happened, despite medical technology being BAD in Europe at the time, until mid to late Victorian era.
Wouldn't they evolve to the different conditions?
In any case, "tundra" more or less describes the temperate regions. Grassland and Boreal Forest cover areas closer to the equator, and even temperate rainforest, if you're lucky.
I'm going to add that now. It's not reasonable to assume the entire planet is a single biome.
Are you assuming Earth is one national entity for your timeline, a swarm of private or public entities...?

Please do. I don't want to have this thread locked.
I said 2100, because of the association with @ChrisSpace's Alternate Solar System. I disagree, and think that even OTL Mars would have at least 1 or 2 bases on Mars by the end of the century. At least I hope

... a HABITABLE Mars would have air pressure similar to Earth, or at least 80-90 %. Meaning Maglevs would be about the same speed as on Earth. Maglevs can only reach 603 km/h, and require expensive tracking that won't be viable on Mars until cultures and colonies have fully developed. Sea, road, and conventional Rail are cheap, and are the primary modes of transport- and will likely remain so, because cost is much more important than speed in a world where most people still don't regularly travel cross-country, and cargo generally doesn't care how long it takes to get there.
I'm talking about Native influence. South America, there tended to be a lot more natives around, and the colonists regularly interbreeded. That might be the case in the equilateral region (thus creating a sort of new species), but everywhere else, there isn't going to be many mixed race people, or native influence, like in North America.
A Mars with a breathable atmosphere and easily farmable land and regularly flowing water is much more appealing and makes colonies much more easily sustainable than OTL Mars- which would essentially be like Vostok Base, except cooler, and millions of kms away from Earth. And no breathable atmosphere.
You could get stranded in this Mars, and reasonably survive, you won't on OTL Mars, unless you're Matt Damon.
Of course, we could just robot our way into this entire thing, and colonize Mars with robots. Bu that opens a whole new can of worms.

Like in South America? Maybe. But what if there are much less, like in North America?
Regional Diversity would likely decline, but remember that rocket travel is still hard. Hopping small distances is possible, but intercontinental travel requires about as much you would need to get to Martian Orbit (more if you include precision landing). So I would expect there to still be dominant "types" of cultures, especially in different "national land claims".
New York to Caracas was probably easier than New York to London, and yet developed completely different cultures.